“America already has a military branch for space operations. The Air Force handles military rocket launches, develops most of the Pentagon's spacecraft and tracks satellites on behalf of the whole government, while leaving room for the Army and Navy to undertake certain niche space missions of their own. Creating a separate branch for space wouldn't mean more or better rockets and satellites. But it would mean more bureaucrats.”

Daily Beast

A new branch will likely lead to increased inefficiencies and competition between the branches.

"The priorities of the other services in space will necessarily conflict with the priorities of the Space Force itself.

Lastly, “at least for now... cyberattacks against the United States are more urgent threats than the militarization of the final frontier, and an entirely new service branch seems unnecessary. In the past several years, the military's focus — as Defense Secretary James Mattis noted last year in opposing the idea — has been to better integrate existing services to reduce overhead and duplication.”

“In an address to Congress in 1961, President Kennedy challenged America to send astronauts to the moon and back before the end of the decade. Mr. Kennedy said that it’s ‘time for this nation to take a clearly leading role in space achievement, which in many ways may hold the key to our future on Earth.’ That’s true in 2018 as well, and it’s not such a crazy idea at all.”

Washington Times

“It is true that the existing branches maintain capabilities that extend into space...

But American air power was once the province of the U.S. Army and Navy, and bureaucratic elements within these two branches opposed the creation of a U.S. Air Force in 1947. The importance of air power in World War II and the likelihood that aircraft would be a critical feature of future warfighting convinced policymakers that

. The Chinese created something called the PLA Strategic Support Force on December 31, 2015. That includes their space forces as well as their hacking units...

The Russians created the Russian Aerospace Forces at about the same time, actually a little bit before. Both of our key potential adversaries have been thinking about warfighting in space for three, four, five years.”

Breitbart

In response to those who “argue that the international space treaties ensure the peaceful use of space... If international treaties were so effective in keeping the peace, why hasn’t someone created a set of treaties for the peaceful use of the Earth? What makes space so different from the other strategic domains of land, sea, and air?”